MARS PETCARE ACADEMY 玛氏宠物护理学院

玛氏宠物护理学院

在中国,为宠物创造一个更美好的世界

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猫的进食行为和喜好
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Following a BSc and PhD in Nutrition Dr Richard Butterwick spent a short sabbatical lecturing pre-clinical studies at the Samora Machel Veterinary School, Lusaka, Zambia, before joining the Department of Paediatric Endocrinology at Saint Bartholomew's Hospital, London where he was part of a clinical research team working on growth disorders in children. In 1991 Richard joined the Clinical Nutrition team at WALTHAM. Richard has been published widely in the field of dog and cat nutrition and is a member of a number of professional bodies.

Richard Butterwick获得学士和营养学博士学位后利用短暂的学术休假时间在赞比亚卢萨卡Samora Machel兽医学校教授临床前研究,然后加入了伦敦Saint Bartholomew医院儿科内分泌科的临床科研组,研究儿童的发育失调。1991年,Richard加入了威豪的临床营养学团队。他发表了多篇猫狗营养学方面的文章,是许多专业机构的成员。

Key Message

关键信息

WALTHAM has contributed to the understanding of the feeding behaviour and food preferences of the cat by:

威豪一直致力于理解猫的进食行为和偏好,主要是

  • Generating insights into the inherited behavioural strategies that influence when they eat, what they eat, and how much they eat.
  • 通过对遗传行为的科学研究,以洞察哪些因素决定猫何时进食、吃些什么和吃多少。
  • In collaboration with the Monell Chemical Senses Center, identifying the molecular mechanism underlying the cat’s indifference to sweet taste.
  • 与Monell化学知觉中心合作,确定导致猫对甜味无感觉的分子作用机制。
  • Demonstrating that cats seek out particular nutrients in their food.
  • 证明猫通过食物寻找特定的营养素。

Background

背景知识

It comes as no surprise to many owners that domestic cats are often described as finicky feeders (Bradshaw and Thorne 1992). In fact, the feeding preferences of cats are highly individual (Thorne 1994). Owners frequently report that their cat has apparently idiosyncratic food preferences, examples being particular food items or a liking for or refusal of one particular product or flavour from a commercial range.

家养的猫往往比较挑嘴,许多宠物的主人并不会对此感到惊讶(Bradshaw and Thorne 1992)。实际上,猫的进食偏好是非常独特的(Thorne 1994)。主人通常反映他们的猫拥有看起来较为独特的食物偏好,例如某些具体的食品或喜欢或者拒绝某个商品序列的产品或味道。

Cats are predators and obligate carnivores, and in the wild their diet is composed of a variety of items, especially small mammals, with some birds, reptiles, insects and very little vegetable matter (Plantinga et al. 2011). Availability is undoubtedly one factor, such that the feline diet may be restricted within a locality or season. In addition, the nutrient content can differ not only between different prey species but also within a species; depending, for example, on the time of year or the age of the prey animal. Coping with a food supply that is unpredictable in terms of availability and nutrient content requires particular behavioural strategies. These have been inherited by the domestic cat from its ancestors and probably underlie much of the feeding behaviour seen today.

猫是食肉动物,也是专性食肉动物,野生猫的食物包括各种肉类,尤其是小型哺乳动物,还有某些鸟类、爬虫、昆虫和极少数的植物性物质(Plantinga et al. 2011)。毫无疑问,能否捕到猎物永远是个问题,同时,猫科动物的食物可能局限在某一地区或受季节而定也是一个问题。此外,猎物种类不同,营养成分也会不同,即便是同一种类的猎物也会有不同的营养成分;例如,这取决于季节因素以及猎物的年龄。食物供应是不可预测的,受到猎物的可获得性和营养成分的限制,要应对这种状况就需要独特的行为策略。家猫从祖先那里遗传了这些行为策略,很可能正是这些策略决定了今时今日家猫展现出的很多摄食行为。

As in all species, taste is an important factor determining what cats like to eat. Unlike dogs (Ferrell 1984) and humans (Reed and McDaniel 2006), cats show no preference for, and indifference to, sweet compounds (such as sugars and artificial sweeteners). It seems that having evolved as an obligate carnivore the ability to taste sugar was lost and today’s cats have inherited this.

就像所有物种一样,味道是决定猫的进食喜好的重要因素。与狗(Ferrell 1984)和人类(Reed & McDaniel 2006)不同,猫不喜欢或者说对甜味化合物(例如糖和人工甜味剂)无感。似乎在进化成专性食肉动物的过程中,它失去了对甜味的味觉,现在的猫遗传到了这一点。

Evidence from a number of species ranging from insects to mammals (including cats) indicates that they are well adapted to dealing with a food supply of varying nutritional content by balancing their intake of macronutrients (protein, fat and carbohydrate) through adjusting their intake of different foods (Simpson and Raubenheimer 2012).The optimal macronutrient profile for the cat is one which best matches its nutritional and metabolic needs – which might be expected to vary depending on physiological state (for example growth, adult maintenance or reproduction).

证据显示,许多物种,从昆虫到哺乳动物(包括猫),都能适应不断变化的营养成分,通过调整各种食物的摄入量以均衡宏量营养素(蛋白质、脂肪和碳水化合物)的摄入量。对猫而言,最佳的宏量营养元素组成应能够满足其营养和新陈代谢需求-随生理状态的变化这些需求可能会有所变化(例如发育期、成猫维持期或生产期)。

Understanding the complex feeding behaviour and preferences of the cat is a challenge. Multiple factors determine when cats eat, what they eat and how much they eat – including inherited attributes, dietary nutrient content, the cat’s physiological state and the owner’s behaviour.

理解猫复杂的进食行为和偏好是一种挑战。多种因素决定了猫何时进食,吃些什么以及吃多少-包括遗传因素、膳食营养成分、猫的生理状态和饲主的行为。

 

Why WALTHAM is Interested

威豪对此感兴趣的原因

To produce diets that cats like – and continue to like – requires a fundamental understanding of the basis of cat feeding behaviour and preference.

为了制作猫喜欢并且继续喜欢的食物,需要了解决定猫进食行为和偏好的基础性决定因素。

 

Approach

方法

Cats have inherited feeding behavioural strategies from their ancestors and early studies were directed at gaining insight into these.

猫从祖先那里遗传了进食行为,早期研究便旨在加深此方面的了解。

Later, molecular techniques were used to investigate the expression of the genes encoding the sweet taste receptor in the cat.

后来,人们利用分子技术调查遗传因子的表达,解密猫甜味受体的遗传密码。

Other studies used diets with a range of macronutrient profiles and sophisticated modelling techniques to determine how the macronutrient content of the diet influences food intake.

其他研究则利用各种宏量营养素组成比例和复杂的模化技术来确定膳食中的宏量营养成分如何影响摄食。

 

Insight Generation(Feeding Behavior)

独特观点(进食行为)

Cats exhibit inherited behavioural strategies that influence when they eat, what they eat and how much they eat

猫显现出的遗传行为影响了进食时间、进食内容和食量。 

Domestic cats have inherited the behavioural strategies used by their ancestors to cope with an unpredictable food supply, and these probably underlie much of the feeding behaviour seen today. Early studies at WALTHAM generated insight into these behaviours which influence when cats eat, what they eat and how much they eat.

家猫遗传了祖先的行为,猫的祖先利用这些行为来应对变化莫测的食物来源,进而决定了今天所见的众多摄食行为。威豪中心的早期研究主要是深入认识这些影响猫进食时间、进食内容和食量的行为。

A major factor influencing when cats eat, as well as how much they eat, is food availability. When food availability is not restricted, cats eat small, frequent meals. Studies at WALTHAM showed that if cats have constant access to an acceptable food, they take intermittent small meals throughout the 24-hour period (Bradshaw and Thorne 1992). The number and size of meals varies with the individual, generally ranging from 7–16, with around 13.3 per day (Figures 1 -2) (Mugford and Thorne 1980; Bradshaw and Thorne 1992; Mugford 1977; Thorne 1982). Restricting food availability to meal times means that the cat eats larger, less frequent meals. Cats adapt their meal size and meal frequency based on the availability of food (Bradshaw and Thorne 1992).  

影响猫进食时间和食量的重要因素是食物的可获得性。当食物的可获得性不受限时,猫就会少食多餐。威豪的研究显示如果猫能够经常吃到中意的食物,一天24小时中它们会断断续续地一点一点地吃(Bradshaw &Thorne 1992)。进餐的数量和质量对于每只猫来说各有不同,通常而言从7次到16次都有,一天大约13.3次(见图1-2)(Mugford & Thorne 1980; Bradshaw & Thorne 1992; Mugford 1977; Thorne 1982)。通过限定进餐时间来限制食物可利用性意味着猫每一餐会吃得更多,进餐次数会减少。猫根据食物的可获得·性来调整它们的食量和进餐频率(Bradshaw & Thorne 1992)。

 

Reproduced from Bradshaw J, Thorne C. Feeding Behaviour. In: The Waltham Book of Dog and Cat Behaviour. Editor: C Thorne. Pergamon Press, New York. 1992, Chapter 7 pages 115-129.

摘自Bradshaw J, Thorne C.著《摄食行为:威豪小册子之猫狗行为》,C Thorne编写,纽约Pergamon Press出版社出版,1992,第7章第115-129页。

Reproduced from Bradshaw J, Thorne C. Feeding Behaviour. In: The Waltham Book of Dog and Cat Behaviour. Editor: C Thorne. Pergamon Press, New York. 1992, Chapter 7 pages 115-129.

摘自Bradshaw J, Thorne C.著《摄食行为:威豪小册子之猫狗行为》,C Thorne编写,纽约Pergamon Press出版社出版,1992,第7章第115-129页。

Figure 1: The 24-hour meal patterning of cats given free access to a dry food (Bradshaw and Thorne 1992). Meals are taken at irregular intervals throughout the day and night. The size and frequency of meals is characteristic of the individual cat.

图1:能够自由获取干粮的猫的24小时进食图(Bradshaw  & Thorne 1992)。全天候不定时摄食。进食多少和频率也是每只猫都有不同。

 

Other factors influencing what cats eat and how much they eat, include neophobia and monotony. These are evolutionary behavioural strategies that are common in many species. When first offered a new food, cats can be neophobic. If they are fed the same diet over a long period they may become bored (the product may be perceived as monotonous). They may then become less neophobic and seek out new food choices (neophilia). Neophobia probably safely establishes the non-toxicity or nutritional adequacy of new food items. The evolutionary basis of monotony is probably to prompt the animal to seek a varied diet to guard against the nutritional inadequacy of any one food item.

其他影响猫的进食种类和频率的因素包括新物反应和对旧事物的厌倦。这些属于进化行为,在许多物种中都很常见。第一次被喂给新食物时,猫会感到恐惧。如果长时间喂食同一种食物,它们可能会感到厌倦(食物会被视作单一无味的)。届时它们便不再那么恐惧,会主动外出寻找新的食物(喜欢新奇食物)。新物反应逐渐确定了新食物的无毒性和营养丰富度。厌旧的进化基础可能是促使动物寻找各种各样的食物,以应对单一食物的营养缺失。

Studies show that cats exhibit neophobia when presented with new food items (Bradshaw et al. 2000). When presented with a novel food, cats eat a small amount on the first occasion before subsequently increasing their intake (Figure 3 Bradshaw 1986). Alternatively, the cat may completely reject the new food, particularly if it is very unusual, or undertake extensive sniffing first (O’Malley 1995). Neophobia is less evident in cats with a wide experience of different foods, is more evident when the cat is in a new environment and can usually be overcome by repeatedly offering the new food (O’Malley 1995).

研究证明,给猫新食物时它会产生新物反应(Bradshaw et al. 2000)。面对新奇食物,猫第一次会先吃一点点,然后逐渐加大摄入量(图3,Bradshaw 1986)。甚至猫会完全拒绝新食物,特别是当食物非常罕见之时,猫也可能会先前前后后地把食物嗅个遍(O’Malley 1995)。对于吃过不同食物的猫而言,新物反应则不那么明显;而对于处于新环境中的猫这一反应则更加显著一些,不过通常反复给与新食物可以让猫克服怕生心理(O’Malley 1995)。

 

Reprinted from Bradshaw JWS. Mere exposure reduces cats' neophobia to unfamiliar food. Animal Behaviour 1986; 34(2):613-614 with permission from Elsevier

摘自Bradshaw JWS著《简单的接触可以减少猫对陌生食物的新物反应》,《动物行为》,1986; 34(2):613-614,获Elsevier批准


图2:猫在第一次遇到新食物时会出现新物反应(Bradshaw 1986)。针对两组猫在5个测试日内对喜好食物的进食情况平均百分比(第二组第一天未接受测试)。第一天食物摄入量较低,随后逐渐增加(第8天和第9天)。停止给猫吃这种食物的第102天,新物反应再次出现,第112天进食量小。

Figure 2: Cats show neophobia on first presentation of a novel food (Bradshaw 1986). Mean percentages of flavoured food eaten on 5 test days by two groups of cats (group 2 was not tested on day 1). Food intake is low on day 1 but subsequently increases (days 8 and 9). After a 102-day break from the food, neophobia returns, with low intake on day 112

 

Other studies at WALTHAM showed that cats exhibit neophilia, in that when repeatedly fed the same food they seek variety in their diet. If cats are repeatedly fed a single food, its palatability transiently decreases (Mugford 1977). This monotony is evident as a gradual decline in the intake eaten at each meal (Figure 4). Subsequently, the cat exhibits neophilia, choosing alternative foods. When kittens that have been raised exclusively on one diet are offered it or an alternative, they choose the alternative (Figure 5-6) (Mugford 1977).

威豪的其他研究发现猫喜欢新奇事物,因为当反复喂养同一种食物后它们会在膳食中寻求变化。如果反复喂养猫单一食物,食物的适口性会有短暂的降低(Mugford 1977)。从每一餐逐渐减少的进食量可以明显看出这种厌旧心理(图4)。随后,猫会对新食物产生强烈兴趣,选择其他食物。如果一直给小猫吃单一膳食,当给它另外一种可供选择的食物时,它们会选择后者(图5-6)(Mugford 1977)。

 

Reproduced from O'Malley S. The role of variety in the diet. Waltham Focus 1995. 5(3):18-22

摘自:O'Malley S著《膳食多样化的作用》,Waltham Focus 1995. 5(3):18-22

 

 

Figure 3: Repeated feeding of a single food results in a decline in intake as it becomes less preferred (diet A), which is restored upon feeding an alternative (diet B), providing it is contrasting (O’Malley 1995). Cats can show a rapid monotony response to some foods 

图3:反复喂食单一食物导致进食量减少,因为食物越来越不受猫喜爱(膳食A);当给与另一种食物(膳食B)时,如果两种食物有所差异(O’Malley 1995),猫会恢复好胃口(O’Malley 1995)。对于一些食物,猫会迅速显示出厌旧反应。

 

Reprinted from Mugford RA. External influences on feeding of carnivores. In: The Chemical Senses and Nutrition. Editors: Kare MR, Maller O. Academic Press, New York 1977, Chapter 2 P25-48

摘自Mugford RA.著《对食肉动物摄食的外界影响》,The Chemical Senses and NutritionKare MR, Maller O编,Academic Press 出版社出版,New York 1977,2章第25-48

Reprinted from Mugford RA. External influences on feeding of carnivores. In: The Chemical Senses and Nutrition. Editors: Kare MR, Maller O. Academic Press, New York 1977, Chapter 2 P25-48

摘自Mugford RA.著《对食肉动物摄食的外界影响》,The Chemical Senses and NutritionKare MR, Maller O编,Academic Press 出版社出版,New York 1977,2章第25-48

 

Figure 4: After kittens have been reared on a single canned product, they show preference for a novel alternative (Mugford 1977). In the top panel kittens maintained on liver variety cat food show a preference for the chicken variety for the first few days it is offered. In the bottom panel kittens maintained on the chicken variety cat food show an initial preference for the liver variety

图4:用单一的罐装猫粮喂养小猫时,它们会对新奇的食物展示出偏好(Mugford 1977)。上面那组一直吃肝脏类猫粮的小猫在头几天对鸡肉类猫粮表示出偏好。下面那组一直吃鸡肉类猫粮的小猫则一开始则喜欢肝脏类猫粮。

These early studies revealed the complexity of cat feeding behaviour and certainly contribute to the perceived fussiness of some individuals, as described by their owner.

这些早期研究显示了猫摄食行为的复杂性,这些复杂的习性导致了一些猫的挑食习惯,正如饲主们所描述的那样。

 

Discovery (Sweet Taste)

发现(甜味觉)

Cats are indifferent to sweet taste because the Tas1r2 gene is not functional, so the sweet taste receptor cannot be formed

猫对甜味无感觉,因为Tas1r2基因未发挥作用,因此无法形成甜味受体

In contrast to dogs (Ferrell 1984) and humans (Reed and McDaniel 2006), cats show no preference for, and indifference to, sweet compounds (such as sugars and artificial sweeteners). However the mechanism underlying this was unknown.

与狗(Ferrell 1984)和人类(Reed & McDaniel 2006)不同,猫不太喜欢或者说对甜味化合物无感觉(例如糖和人工甜味素)。不过人们过去并不清楚导致这一原因的生理结构。

In collaboration with the Monell Chemical Senses Center, Philadelphia, the two genes known to be responsible for the sweet taste bud receptor in other mammals were investigated in the cat (Li et al. 2005; Li et al. 2006).

与费城Monell化学知觉中心合作,威豪研究了猫体内两类已知的、对其他哺乳动物的甜味蕾受体起控制作用的基因(Li et al. 2005; Li et al. 2006)。

One of the genes – Tas1r3 – was expressed normally in cat taste buds (Li et al. 2005), as might be expected because it is also involved in the perception of umami taste, which cats are known to recognise. The cat Tas1r3 gene was found to be very similar to the dog (Figure 7), human, and rodent genes; at both the cDNA (74–87%) and deduced amino acid (72–85%) level (Li et al. 2006).

其中一类基因- Tas1r3-通常出现在猫的味蕾中(Li et al. 2005),据估计它也参与了鲜味的感知过程,而据我们所知猫是可以尝出鲜味的。我们发现猫的Tas1r3基因与狗、人类和啮齿目动物在cDNA(相似度为74–87%)和推定的氨基酸序列(72–85%)上非常类似(图7)(Li et al. 2006);

 

Reproduced from Li X, Li W, Bayley DL, Cao J, Reed DR, Bachmanov AA, Huang L, Legrand-Defretin V, Beauchamp GK, Brand JG. Cats lack a sweet taste receptor. J Nutr 2006. 136(7Supp):1932S-1934S摘自Li X, Li W, Bayley DL, Cao J, Reed DR, Bachmanov AA, Huang L,Beauchamp GK, Brand JG.,《猫缺乏甜味受体》,J Nutr 2006. 136(7Supp):1932S-1934S

 

Figure 5: Gene structure of Tas1r3 and Tas1r2 for cat and dog (Li et al. 2006).  The exons are shown in black (size in bp). Location (bp) refers to the position within each exon. Intron sizes shown in the figure are not proportionally scaled in (A) or (B) because of the large size of the Tas1r2 introns. Under each dog exon is the percentage of similarity between that exon and its cat counterpart at the nucleotide level (B). The exons for cat Tas1r2 refer to parts corresponding to dog exons. Asterisks indicate the position of microdeletion in exon 3 as well as the stop codon positions in exons 4 and 6 of cat Tas1r2. The accession for dog Tas1r3 is AY916759, and for dog Tas1r2 is AY916758

图5:猫狗的Tas1r3 及 Tas1r2基因结构(Li et al. 2006)。黑色的是外显子(大小以bp为单位)。位置(bp)指的是在每个外显子内的位置。(A)图和(B)图中显示的内含子大小并不是按比例的,因为Tas1r2内含子较大。狗的外显子下方标的是狗的外显子与猫的外显子在核苷酸层面(B)的相似百分比。猫的Tas1r2基因的外显子指的是与狗的外显子相对应的部分。星号指的是猫的Tas1r2基因中外显子3的微缺失位置、外显子4和外显子6的终止密码子位置。狗的Tas1r3基因的收录号是AY916759,Tas1r2基因的收录号是AY916758。

 

The other gene – Tas1r2 – was found to have a 247-base pair microdeletion in exon 3 and stop codons in exons 4 and 6 in the cat (Li et al. 2005). There was no evidence of detectable mRNA by reverse transcription polymerase chain reaction or in situ hybridisation, and no evidence of protein expression by immunohistochemistry (Li et al. 2005). This was the case in six healthy adult domestic cats as well as a tiger and a cheetah, and shows that, in the cat, Tas1r2 is an unexpressed pseudogene (Li et al. 2005).

威豪发现猫的另一个基因- Tas1r2-在外显子3上拥有一个247碱基对的微缺失,外显子4和外显子6有终止密码子(Li et al. 2005)。通过逆转录-聚合酶链反应或原位杂交反应没有发现可测的mRNA,通过免疫组织化学技术也没有发现蛋白质表达的迹象(Li et al. 2005)。6只健康的家猫是这样,一只老虎和一只非洲豹也是这样,这说明在猫体内,Tas1r2基因是未表达的假基因(Li et al. 2005)。

Because the Tas1r2 gene is not functional in the cat, the sweet taste receptor cannot be formed and so the cat cannot taste sweet stimuli. It is likely that due to its evolution as an obligate carnivore, pressure to retain this gene was not maintained in the cat.

由于猫体内Tas1r2基因未起作用,便无法形成甜味受体,从而使得猫无法尝出甜味刺激。这可能与猫进化为专科食肉动物有关,猫体内保持这种基因的压力已经消失了。

 

Discovery (Preferred Macronutrient Profile)

发现(首选的宏量营养素构比)

Cats seek out particular nutrients in their food choices

猫在选择食物时会寻找独特的营养素

In trying to understand the complex feeding behaviour of cats, WALTHAM was inspired by research from an unusual source – insect nutrition!

为了理解猫复杂的摄食行为,威豪从一个独特领域的研究-昆虫营养学-受到了启发。

Scientists at the University of Oxford, UK, (Professor Stephen Simpson [now at University of Sydney, Australia] and Professor David Raubenheimer [now at Massey University, New Zealand]) had developed a nutritional model (Geometric Framework) which they used to explain how insects such as locusts and caterpillars faced with choices of foods containing different amounts of nutrients (e.g. protein and carbohydrate) adjusted their intakes of the foods to end up consuming a particular amount of protein and a particular amount of carbohydrate. They proposed that this balance and amount of nutrients selected by animals represents their ‘intake target’ and showed that this point is associated with optimal performance, measured in terms of evolutionary fitness (Raubenheimer and Simpson 1997; Simpson et al. 2004).

英国牛津大学的科学家Stephen Simpson教授(目前在澳大利亚悉尼大学任教)和David Raubenheimer教授(目前在新西兰Massey大学任教)开发出了一种营养学模型(几何框架)。他们利用这一模型解释像蝗虫和毛虫这样的昆虫在面对含有不同含量的营养素(例如蛋白质和碳水化合物)的食物选择时如何调整食摄入量,从而最终消化掉特定数量的蛋白质和碳水化合物。他们提议动物选择营养素的平衡性和数量代表了它们的“摄食目标”,并且表明这个“摄食目标”是为了追求最佳的生理表现,此发现可以通过遗传适合度这个测量指标予以说明(Raubenheimer & Simpson 1997; Simpson et al. 2004)。

 

So if insects regulate their macronutrient intake, what about cats?  Carnivorous animals were not thought to regulate their intake of protein, fat and carbohydrate. This was based largely on the assumption that the composition of different prey species is less variable in nutrient composition than the foods of herbivores and omnivores and such mechanisms are therefore unnecessary.

因此,如果昆虫可以规范它们的宏量营养素摄入量,猫又是怎样的呢?在人们看来,食肉动物不会规范自己的蛋白质、脂肪和碳水化合物的摄入量。依据是人们假设比起食草动物和杂食动物的食物,不同种类的猎物在营养素组成上缺乏变化,因此这种规范摄入量的机能是不必要的。

In collaboration with Professors Simpson and Raubenheimer, WALTHAM used the Geometric Framework to investigate whether cats showed evidence of regulating their macronutrient intake.

通过与Simpson 教授及Raubenheimer教授的合作,威豪利用几何框架研究猫是否展示出了规范营养素摄入量的迹象。

In an extensive series of feeding studies, the effect of dietary macronutrient profile (the relative amounts of protein, fat and carbohydrate) on the food intake of adult cats was investigated. For these studies, 12 nutritionally-complete diets (6 extruded [dry] and 6 canned [wet]) were specially formulated to achieve a range of macronutrient energy ratios. Cats were offered different choices of the wet foods or the dry foods in order to self-select a diet (macronutrient) composition of their choice. Geometric techniques combining mixture triangles and intake plots from the geometric framework were used to tease apart the complex interactions among protein, fat and carbohydrate in the regulation of food intake (Hewson-Hughes et al. 2011).

在一系列摄食行为研究中,调查了膳食中宏量营养素组成比例(蛋白质、脂肪和碳水化合物的相对数量)对成年猫食物摄入量的作用。这些研究特别设计了12种营养全面的膳食(6种膨化食品【干】和6种罐装食品【含水】),以提供广泛的宏量营养素能量比例。提供给猫含水食品和无水食品的选择,以便让它们自己选择一种膳食(宏量营养素)结构。利用几何方法分解摄食调节中蛋白质、脂肪和碳水化合物复杂的交互作用。这种几何方法融合了混合三角形和几何框架中的摄入量曲线(Hewson-Hughes et al. 2011)。

This research revealed strong nutritional regulation of food intake in cats and identified a target intake of approximately 26 g/day protein, 9 g/day fat, and 8 g/day carbohydrate, providing a macronutrient energy composition of 52% protein, 36% fat and 12% carbohydrate (Hewson-Hughes et al. 2011). When provided with food choices that did not allow them to achieve this target intake the cats got as close as they could by adjusting their intakes of the foods provided (Figure 8). These studies also found that cats have a limit on the amount of carbohydrate they are willing to eat in a day (~300 kJ/day which is approximately 20 g/day) – termed the ‘carbohydrate intake ceiling’ – which limits further food intake. Hence, cats confined to a high carbohydrate diet had reduced food intake and deficits in protein and energy intake relative to the target intake (Hewson-Hughes et al. 2011). Work in other species suggests that the target intake is not fixed, but may change in response to the animals’ physiological and environmental circumstances (Raubenheimer and Simpson 1997). Ongoing work at WALTHAM is investigating the target macronutrient profiles of kittens during growth and queens during gestation and lactation.

这项研究揭示了猫强大的摄食营养调节能力,发现目标摄入量约为蛋白质26克/天、脂肪9克/天和碳水化合物8克/天,宏量营养素的能量组成为52%蛋白质、36%脂肪和12%碳水化合物(Hewson-Hughes et al. 2011)。当供猫选择的食物无法达到这一目标摄入量时,它们会根据食物调整摄入量以便尽可能接近目标(图8)。研究还发现每天猫愿意吃入的碳水化合物是定量的(300千焦/天,即大约20克/天)-称之为碳水化合物摄入上限-这限制了它们吃进更多食物。因此,只能吃到高碳水化合物食品的猫减少了食物摄入量,在蛋白质和能量摄入量上无法达到目标(Hewson-Hughes et al. 2011)。对于其他动物的研究发现,目标摄入量并不是固定的,随着动物生理和环境的变化也会有所浮动(Raubenheimer and Simpson 1997)。目前威豪正在开展的工作是研究小猫在生长期间的目标宏量营养素组成比例以及母猫在怀孕和哺乳期间的目标宏量营养素组成比例。

 

Reproduce/adapted with permission from The Journal of Experimental Biology: Hewson-Hughes AK, Hewson-Hughes VL, Miller AT, Hall SR, Simpson SJ, Raubenheimer D. Geometric analysis of macronutrient selection in the adult domestic cat, Felis catus. J Exp Biol.2011;214(6):1039-1051获实验生物学杂志批准,复制自/改编自Hewson-Hughes AK, Hewson-Hughes VL, Miller AT, Hall SR, Simpson SJ, Raubenheimer D. 著《成年家猫宏量营养素选择的几何分析》,Felis catus. J Exp Biol.2011;214(6):1039-1051

 

Figure 6: The influence of dietary macronutrient profile on food intake in the cat (adapted from Hewson-Hughes et al. 2011) The blue triangle encompasses the wet diet treatments, and the red star indicates the position of the intake target. The brown triangle shows dry diet treatments, with the red circle showing the intake selected by cats restricted to these diets

图6:猫摄入食物中膳食宏量营养素组织比例的影响(调整自Hewson-Hughes et al. 2011)。蓝色三角形包含了含水食品,红色五星则显示的是目标摄入量的位置。褐色三角形显示的无水食品,红圈则是受限于这些食品的猫选择的摄入量。

 

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